diff --git a/lib/Drupal/chessboard/Plugin/Field/FieldType/ChessboardItem.php b/lib/Drupal/chessboard/Plugin/Field/FieldType/ChessboardItem.php
index a7b9103..c5e0b80 100644
--- a/lib/Drupal/chessboard/Plugin/Field/FieldType/ChessboardItem.php
+++ b/lib/Drupal/chessboard/Plugin/Field/FieldType/ChessboardItem.php
@@ -60,7 +60,7 @@ class ChessboardItem extends FieldItemBase {
         'Length' => array(
           'max' => 64,
           'min' => 64,
-          'exactMessage' => t('%name: must be 64 characters long.', array('%name' => $this->getFieldDefinition()->getLabel())),
+          'exactMessage' => t('%name: piece placement text must be 64 characters long.', array('%name' => $this->getFieldDefinition()->getLabel())),
         ),
       ),
       ));